Since 1977 when Father Wu Ruo demonstrated his therapy on arthritis by massage on the sole of foot, the practice has received worldwide attention and become a fad in this country. High demand on this practice has prompted the introduction of various massage appliances and gadgets on the market, which therapeutic effects have been affirmed by the general public. As shown in FIG. 1, which illustrates a type of massage slipper and sole pad easily available on the market, on a sole pad unit 1 are all massaging balls 10, which produce massaging effect when they are in contact with the sole of foot, but its massaging efficiency is quite limited, because the depressed part on the sole of foot will be unable to have any contact with the massaging balls 10, so that is a blind corner. An important fact is that there are many acupoint reflective areas in the depressed part of the sole, which are essential to human health, including, as shown in FIG. 2, heart A, spleen B, prostate gland (uterus) C, uric bladder D, ureter E, kidney F, pancreas G, adrenal gland H, solar nerve cluster I, gall bladder J, liver K, penis (vagina) L, etc., as a result, it could not achieve the effects during its application; there is another model of massage slippers, as shown in FIG. 3, which involves several pebble-shaped toe bridges 20 on a sole plate 2 to correspond to the positions of toes, and on the locations corresponding to the depressed part of the sole of foot are pebble-shaped protrusion 21 and burg-shaped protrusion 22, such slippers will improve the shortcoming of aforementioned prior art of slippers, but its improvement is merely partial, since although there is the pebble-shaped protrusion 21 on the depressed part of the sole, it involves also the burg-shaped protrusion 22 on the heel location, which is inconsistent with ergonomic principle, as indicated by the distribution of body weight on human feet, the weight is supported by the foot palm and the heel, since the pebble-shaped protrusion 21 and the depressed part of the sole are only in slight contact, it has limited effects on the various reflective areas on the depressed part of the sole of foot, and since the height of the burg-shaped protrusion 22 on the heel position is too high, it results in insufficient contact between the pebble-shaped protrusion 21 and the depressed part of the sole, therefore, it could not have real effects; the Japanese have come up with a type of health slippers to enable effective massage on the acupoint reflective areas or, the depressed part of the sole, which, popularly known as "Japanese slippers", is shown in FIG. 4. Said slippers have a length of about 2/3 of that of the foot, the massage effect can be achieved since the depressed part of the sole is justly located at the end of the slipper, since the user's heel is not in contact with the floor when he is wearing such a type of slippers, the depressed part of the sole can be massaged by the end part of the slipper, but it has been indicated by medical researchers that said slippers will result in deformation on the feet after they are worn for an extended period of time since the heels are not in contact with the floor, which is bad to human health, and said slippers are not suitable for outdoor use which would be considered vulgar by the society, therefore, they need improvement.
In view of the aforementioned drawbacks of conventional models of slippers, the subject inventor has utilized several years experience in the production of shoe-sole pads, accompanied by the research in sole massage reflective areas, and has come up with the subject invention.